Merge bitcoin/bitcoin#29115: [doc]: add doxygen comment describing what CheckPackageLimits returns

19bb65b [doc]: add doxygen return comment for CheckPackageLimits (ismaelsadeeq)

Pull request description:

  This PR adds a  doxygen comment on `CheckPackageLimits` describing what the method returns.

  Fixes bitcoin/bitcoin#28863 (comment)

ACKs for top commit:
  Sjors:
    utACK 19bb65b
  Zero-1729:
    utACK 19bb65b

Tree-SHA512: ccf1cc00a44d3fff60f28ad6766019a9f61b349729eab3cb02bc76b13c2e55441348a1602d806e60e4b2eabeb1f5d1ddacddf86c0bcdb78b078bb3a863b650c2

Author: glozow

src/txmempool.h

@@ -605,6 +605,7 @@ class CTxMemPool
      *                                          to mempool. The transactions need not be direct
      *                                          ancestors/descendants of each other.
      * @param[in]       total_vsize             Sum of virtual sizes for all transactions in package.
+     * @returns {} or the error reason if a limit is hit.
      */
     util::Result<void> CheckPackageLimits(const Package& package,
                                           int64_t total_vsize) const EXCLUSIVE_LOCKS_REQUIRED(cs);